Independence Day(1996) [First Lady Marilyn Whitmore]: Dies (off-screen) of internal bleeding due to injuries from a helicopter crash. We last see her in her hospital bed talking to Bill Pullman; her death is confirmed in subsequent dialogue. (Thanks to Paul, Neil, Drew, and Sheena)

Donnie Darko(2001) [Rose Darko]: Killed in a plane crash, along with her daughter (Daveigh Chase) and everybody else on board, when the plane hits turbulence from the time tunnel. Her son (Jake Gyllenhaal) later alters the timeline and prevents her death. (Thanks to Tommy)

Scream 4(2011) [Kate Roberts]: Stabbed in the back through the mail slot by the masked killer while Mary is standing against the door, as Neve Campbell looks on helplessly. (Thanks to Steve, Andrew, Nyk, and Matthew)